The attack occurred in Spalga village in the North Waziristan tribal area, said the officials, speaking on condition of anonymity because they were not authorized to talk to the media.

The dead included some domestic Taliban militants, said the officials. The area where the strike occurred is dominated by Hafiz Gul Bahadur, a prominent militant commander focused on fighting foreign troops in Afghanistan.

President Barack Obama has ramped up drone strikes against Taliban and al-Qaida militants in Pakistan's tribal region since taking office. He acknowledged the covert CIA-run program publicly for the first time in a recent interview, but he and other U.S. officials refuse to discuss details of the operations openly.

The program has caused tensions with Pakistan. Although the Pakistani government is widely believed to have provided support for the strikes in the past, that cooperation has become strained as its relationship with Washington has deteriorated.

Pakistan kicked the U.S. out of a base used by American drones last year in retaliation for American airstrikes that accidentally killed 24 Pakistani troops at two Afghan border posts on Nov. 26.

The move is not expected to significantly impact drone operations, but the pace of strikes has slowed since the border incident as the U.S. has tried to repair the relationship with Pakistan.

Pakistan also retaliated for the errant airstrikes by closing its Afghan border crossings to supplies meant for NATO troops in Afghanistan. But Pakistani officials have said they expect the government to reopen the border after negotiating higher fees with the U.S.

The tussle with the U.S. has come at a time of domestic turmoil in Pakistan. The Supreme Court has vowed to charge Prime Minister Yousuf Raza Gilani with contempt for failing to reopen an old corruption case against the president. If convicted, the premier could serve up to six months in jail and be disqualified from holding public office.

A defendant can appeal a contempt charge in Pakistan before the case goes to trial.

The government has long refused a Supreme Court order to write to Swiss authorities to reopen a corruption case against President Asif Ali Zardari that dates back to the late 1990s. Officials have argued that the president has immunity from prosecution while in office.